Questions tagged [cisco]

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11
votes
3answers
10k views

1 router, 1 internet connection/IP - multiple VRFs using the same ISP gateway

My knowledge of inter-VRF routing isn't the best. I have one public IP. The public Internet and its quad 0 is on the default VRF.... Then I have a Guest_VRF and a corporate_VRF which would both need ...
6
votes
3answers
4k views

How to throttle speed for a particular computer with high activity?

We're in an office environment of about 50 people. A few departments send emails with large attachments extensively and doing so clogs up the WAN connection (10Mbps). I'm upgrading the networking ...
4
votes
2answers
1k views

Is migrating to VRF or rolling-back an easy proposition?

If VRF is implemented for routing table separation such as having an overlay network for a guest network that doesn't mix with regular LAN routing, is migrating to it easily done on Cisco switches (...
10
votes
1answer
4k views

What's the difference between CRS-1 and CRS-3

What are the differences between the CRS-1 and CRS-3 platforms? I know the CRS-3 is the upgrade to CRS-1. Do I need a new chassis to upgrade to CRS-3? Or is a CRS-1 chassis upgradable to a CRS-3 ...
8
votes
1answer
3k views

How does group-policy inheritance work for a Cisco ASA?

I don't have a lab ASA to confirm this and reading through the Cisco docs left me less then %100 sure. What I really want to know is if I pull an attribute from a group-policy will it then be ...
8
votes
3answers
180 views

How to apply configuration after replacing Routing Engine(RE) for CISCO7609-S?

Senario: I have the backup configuration file. But I don't any USB drive or compact flash card. After replacing the Routing Engine, I tried to copy/paste the configs (around 12k lines) from the ...
13
votes
1answer
2k views

What is the difference between a VRF and GRF? (cisco)

I've heard about VRF's and GRF's, but was is the difference between those 2? (cisco)
2
votes
1answer
134 views

How can I log authentication errors in 3G routers?

What command (debug) can I use to see authentication errors on a cisco 3G router specifically for the 3G connection?
9
votes
3answers
11k views

What is the use of a tunnel interface on a cisco router?

What is a tunnel interface used for on a cisco router? What is the difference between setting up a VPN connection and a tunnel interface; or does this serve the same purpose?
7
votes
2answers
918 views

DSCP trust boundary

I have performed some analysis and noticed that traffic coming in from the Internet contains a myriad of DSCP values. This traffic competes for voice and video resources on the internal network. How ...
5
votes
1answer
2k views

Etherchannel connections between Cisco and Nortel switches

I need to create a 6 port static Etherchannel link between a stack of 3 Cisco 3850's and a Nortel 8310. Can someone provided a basic config for the Nortel side. I have little experience with the ...
12
votes
7answers
14k views

DHCP relay problem on interfaces secondary network

A secondary network was configured on an interface of a Cisco 2621 router and the ip helper-address commands put in place but no clients of that secondary network could pull DHCP addresses. We swapped ...
9
votes
4answers
5k views

CISCO Wireless Lan Controller and AP's design question

There are a couple of questions on design solution. CAPWAP tunnel is created between the controller and the access points. The ends of the tunnel are the controller's "ap-management" interface and ...
8
votes
5answers
15k views

How to test layer 2 connectivity on Cisco Switch?

I'm testing a new FTTH CPE in our lab. A Cisco ME3400 switch. So far I'm having issues in provisioning them. I have activated DHCP debugging to see the DHCP packets. I wonder how can I test to know ...
24
votes
5answers
27k views

Accidentally Removed Allowed VLANs from Cisco Switch Dot1Q Trunk

I am adding a new VLAN to an existing trunk port between two Cisco Catalyst switches (3750's). In the process of adding the new VLAN, it appears that I've removed the existing allowed VLANs on the ...
10
votes
2answers
4k views

How can I disable SIP on IOS 12.x

How would I disable SIP on an Cisco router running IOS 12.x?
6
votes
3answers
378 views

QoS at the edge of branch

I have a question about QoS design in branch. The main place to deploy qos in branch - edge between edge router and ISP. At this edge we have voice traffic to SIP provider, copr. external email and ...
9
votes
3answers
683 views

Why does “show adjacency” take so long to run?

Why does the "show adjacency" command take so long to run (in the order of minutes) on Cisco IOS Software, 7200 Software (C7200P-SPSERVICESK9-M), Version 12.4(4)XD5, RELEASE SOFTWARE (fc1)? The ...
5
votes
5answers
826 views

Can netflow be left on all the time?

One of my colleagues and I have gotten into a debate about netflow. He's an old Cisco hand and I've recently joined the cisco ops team after working on Juniper for a few years. The debate is whether ...
7
votes
6answers
6k views

What is the benefit of a Cisco “top of rack” design?

Aside from the obvious cabling mess you avoid (which I know for us as network engineers is great, but hard to use as an excuse when reasoning with someone who sees no point in it), what do you gain ...
3
votes
1answer
333 views

Source of Cisco NBAR dropped traffic

I recently implemented Cisco NBAR at a remote sites, edge router. to filter and drop P2P traffic. I see the dropped traffic by typing "show policy-map interface XXX" how can i find the source of the ...
1
vote
1answer
723 views

Communication Manager Business Edition 6000 - understanding bundle equipment

I have a Cisco Communication Manager Business Edition 6000 specifications. Can you explain some facts about it. Link to specification According to this, we have BE6K-ST-BDL-K9 (#1) and it contans: 1....
1
vote
3answers
26k views

Why doesn't my port-channel interface come up, between Cisco Catalyst switches?

To connect two Catalyst switch stacks, I use EtherChannel, i.e. I aggregate several ports on each switch to get more bandwidth and higher availability than with just a single port. However, the link ...
6
votes
1answer
2k views

Can FlexConnect ACLs be combined with Local mode ACLs on the same Cisco WLC WLAN?

There's a limitation (stated below in Cisco's documentation) that FlexConnect ACLs in Cisco WLC cannot be combined in the same WLAN with local mode ACLs. The GUI allows the entry of a local mode ACL ...
10
votes
5answers
3k views

How can I speed up CLI typing in Cisco IOS using shortcuts?

I know we can use auto-completion (tab key) and abbreviated commands (such as sh ip int bri) to speed up typing. However, I'm still not satisfied with typing crypting chains such as sh ip dh sn bi | ...
6
votes
1answer
3k views

Cisco 867 forward UDP port range

I need to forward an UDP port range to a specific private IP address in my LAN. In order to forward one port to an internal IP I do: access-list <acc_list_number> permit <port_type> any ...
19
votes
5answers
18k views

Should portfast be used on a port potentially connecting to an unmanaged switch?

I understand the basics of how spanning tree works and why you would want to use portfast on user access ports. When dealing with a topology with a large number of dumb switches under desks and ...
5
votes
3answers
395 views

Cisco Nexus 5000 grounding

I have heard that all 10G switches must be grounded. We have two Cisco Nexus 5000 running for years without any grounding, but I am worried about possible outages caused by ESD. Nexus 5000 has system ...
7
votes
2answers
4k views

Is a DSP required with a SIP trunk?

Assuming a Cisco 3825 router, if the Cisco SCCP phones on the network are using G.711 µ-law and are traversing a CUCME system connected to a SIP trunk that supports G.711 µ-law, is a PVDM2 DSP card ...
14
votes
4answers
4k views

Enabling MLS QoS on a production 7600

I am looking at a 7609-S with a RSP720-3CXL running 12.2(33)SRE3. I have been asked to help with rate limiting some servers attached to a couple of ports running as L2 ports (switchport mode access), ...
13
votes
3answers
5k views

Management network. Best practises: big VLAN or routed interfaces

We are going to deploy a campus network with approximately 50 switches (Core, Agg, Access). Some of them will be L2 (20), and others will be L3 (30). We are thinking about how to manage these devices: ...
9
votes
1answer
17k views

What is the NO PAYLOAD ENCRYPTION version of the IOS software?

When looking at the downloads available on the Cisco site, they have a regular version of the file and a NO PAYLOAD ENCRYPTION version. What is the difference? And why would one choose one over the ...
6
votes
4answers
352 views

Cisco SFP module: Determing Priority?

I have two 3750 Cisco switches that have two fiber cables/sfp modules hooked up on each. The second fiber is just for redundancy. I have installed two new 3750X switches on the rack for the upgrade, ...
10
votes
1answer
19k views

Cisco config example for Policy Based Routing

I find my self in a situation I was in not too long ago, but I can't remember how I resolved it :) The Scenario I have a Cisco IOS router with a LAN interface (fa0/0) and a WAN interface (fa0/1), ...
15
votes
4answers
38k views

How are two “ip helper-address” statements handled?

I've discovered a subnet with two "ip helper-address" statements. This is not our normal configuration. interface Vlan300 ip address 10.1.3.2 255.255.255.0 ip helper-address 10.2.1.10 ip helper-...
6
votes
2answers
511 views

How to use “Pattern Recall” pattern matching in Regex

I'd like to match the 0's in this output, specifically using "Pattern Recall" feature mentioned in Cisco documentation. The pattern is: Gi4/3 0 0 0 ...
10
votes
1answer
368 views

Deconfigure an interface in IOS with one command

I was wondering if there is a single command to clear a single network port's configuration? (wipe switchport, portsecurity,...)
10
votes
3answers
14k views

Cisco: prevent vlan's of communicating with eachother on cisco router (ACL alternative)

Setup: Cisco router with multiple VLAN's configured on it. How can you prevent 2 VLAN's communicating with eachother? Normally I would do this with ACL's like this: access-list 102 deny ip 1.1.1.0 0....
9
votes
5answers
10k views

Monitor specific traffic type on a Cisco router

Is it possible to monitor a specific traffic type going through a cisco router? (like monitoring via wireshark) Ex: I want to monitor http traffic specifically that is passing through a router. (or ...
18
votes
3answers
27k views

How do you know if a Cisco switch is handling traffic well?

I have just read Jeremy's question about 2960-S and iSCSI traffic handling, which drove me to ask this question: We all have lots of switches deployed in distinct infrastructures, how can you know ...
7
votes
1answer
2k views

AP's at remote faciltiy will not join local controller

I currently have a WLC 4404 running 7.0.240.0. Management Interface IP is 10.128.55.10. AP-management interface is 10.128.55.15. Remote facility (facility A) has a VLAN created for wireless (455) ...
6
votes
4answers
7k views

Which is the Preferred location of an IPS within a network? [closed]

In the context of protecting a campus network, which is the Preferred location of an IPS within a network? Within an ISR router IPS as a separate device Within ASA
9
votes
3answers
964 views

ASA Netflow support

Cisco ASAs support a version of netflow called NetFlow Secure Event Logging (NSEL). Is special support for the protocol required on the collectors to view the flows? Is the protocol compatible with ...
7
votes
2answers
720 views

Etherchannel on 6509 (VSS) with interfaces from different type of modules supported?

We currently have 1 10GB Multi-Chassis etherchannel Between 2x 6509 (VSS) and 2x 3750-E (Stack). On the 6509 the etherchannel interface members currently run on the supervisor module VS-S720-10G. We ...
2
votes
4answers
2k views

Cisco 1921 security features in the default bundle

Bought a Cisco 1921 router without any additional modules. This is the first time I'm using a non-home router. What security features should I enable so that users are relatively safe when using the ...
6
votes
2answers
954 views

What are the best Cisco 6500 Ethernet modules for iSCSI?

I have a SAN environment built on FC (Fibre Channel), which is a standalone network from the rest of the DC Ethernet network, and have only Cisco 6509s with Sup720s available for this project. Most ...
17
votes
8answers
17k views

When *not* to create a SVI for a L2 VLAN?

When creating VLANs for just L2 on a switch -- routing will be handled by a device within that VLAN such as a load-balancer -- it isn't necessary to create the vlan interface. As a matter of habit, I ...
5
votes
2answers
4k views

Cisco: No autostate on GigabitEthernet interfaces, any alternative? (not working)

I recently tried the command "no autostate" on a GigabitEthernet interface (on a newer router) and this didn't work anymore, does anyone know why this is occuring? This use to work on FastEthernet ...
21
votes
7answers
35k views

Difference between access list and prefix list?

Can someone explain with an example whats the difference between an access list and prefix list.
10
votes
1answer
5k views

PPPoA ADSL Configuration with external modem on Cisco 891

Context We use Cisco 891 routers as CPE for several client sites. They are all running IOS 15. Cisco IOS Software, C890 Software (C890-UNIVERSALK9-M), Version 15.0(1)M8, RELEASE SOFTWARE (fc1) The ...